The aim of this research was a lab scale study of the influence of calcium and iron supplementations on the yield of methane in batch anaerobic digester treating dairy manure under mesophilic conditions. A gas chromatography analyzer was used to find the percentage of the methane in biogas. Results obtained indicate that both calcium and iron have a positive effect on methane yield. Calcium supplementation up to 200 mg L-1 with an organic loading rate of 60 g L-1 and calcium supplementation up to 2,500 mg L-1 with an organic loading rate of 80 g L-1 and iron supplementation up to 300 mg L-1 with an organic loading rate of 60 g L-1 and iron supplementation up to 400 mg L-1 with an organic loading rate of 80 g L-1 were found to be effective for both ultimate (total) biogas yield and methane yield.